Processing chamber for atomic layer deposition processes

ABSTRACT

A processing station adaptable to standard cluster tools has a vertically-translatable pedestal having an upper wafer-support surface including a heater plate adapted to be plugged into a unique feedthrough in the pedestal. At a lower position for the pedestal wafers may be transferred to and from the processing station, and at an upper position for the pedestal the pedestal forms an annular pumping passage with a lower circular opening in a processing chamber. A removable, replaceable ring at the lower opening of the processing chamber allows process pumping speed to be tailored for different processes by replacing the ring. In some embodiments the pedestal also has a surrounding shroud defining an annular pumping passage around the pedestal. A unique two-zone heater plate is adapted to the top of the pedestal, and connects to a unique feedthrough allowing heater plates to be quickly and simply replaced. In some embodiments the top of the processing chamber is removable allowing users to remove either pedestals or heater assemblies. Or both, through the open top of a processing station. In preferred embodiments the system is adapted to atomic layer deposition processing.

CROSS-REFERENCE TO RELATED DOCUMENTS

[0001] The present invention is a continuation-in-part of co-pendingpatent application Ser. No. 08/920,708 filed Aug. 29, 1997 entitled“Vertically-Stacked Process Reactor and Cluster Tool System for AtomicLayer Disposition” and patent application Ser. No. 08/810,255 filed Mar.3, 1997 entitled “Multipurpose Processing Chamber for Chemical VaporDeposition Processes” which will issue as U.S. Pat. No. 5,855,675 onJan. 5, 1999. The parent applications listed above are incorporatedherein in their entirety by reference and priority to their filing datesis hereby claimed.

FIELD OF THE INVENTION

[0002] This invention is in the field of apparatus and methods forperforming Chemical Vapor Deposition (CVD), and relates moreparticularly to Atomic Layer Deposition (ALD) Processes.

BACKGROUND OF THE INVENTION

[0003] In the field of thin film technology requirements for thinnerdeposition layers, better uniformity over increasingly larger areasubstrates, larger production yields, and higher productivity have been,and still are, driving forces behind emerging technologies developed byequipment manufactures for coating substrates in the manufacturing ofvarious semiconductor devices. For example, process control and uniformfilm deposition achieved in the production of a microprocessor directlyeffect clock frequencies that can be achieved. These same factors incombination with new materials also dictate higher packing densities formemories that are available on a single chip or device. As these devicesbecome smaller, the need for greater uniformity and process controlregarding layer thickness rises dramatically.

[0004] Various technologies well known in the art exist for applyingthin films to substrates or other substrates in manufacturing steps forintegrated circuits (ICs). Among the more established technologiesavailable for applying thin films, Chemical Vapor Deposition (CVD) and avariation known as Rapid Thermal Chemical Vapor Deposition (RTCVD) areoften-used, commercialized processes. Atomic Layer Deposition (ALD), avariant of CVD, is a relatively new technology now emerging as apotentially superior method for achieving uniformity, excellent stepcoverage, and transparency to substrate size. ALD however, exhibits agenerally lower deposition rate (typically about 100 A^(o)/min) than CVDand RTCVD (typically about 1000 A^(o)/min).

[0005] Both CVD and RTCVD are flux-dependent applications requiringspecific and uniform substrate temperature and precursors (chemicalspecies) to be in a state of uniformity in the process chamber in orderto produce a desired layer of uniform thickness on a substrate surface.These requirements becomes more critical as substrate size increases,creating a need for more complexity in chamber design and gas flowtechnique to maintain adequate uniformity. For example, a 75 mmsubstrate processed in a reactor chamber would require less processcontrol relative to gas flow, uniform heat, and precursor distributionthan a 200 mm substrate would require with the same system; andsubstrate size is going to 300 mm dia., and 400 mm. dia is on thehorizon.

[0006] Another problem in CVD coating, wherein reactants and theproducts of reaction coexist in a close proximity to the depositionsurface, is the probability of inclusion of reaction products and othercontaminants in each deposited layer. Also reactant utilizationefficiency is low in CVD, and is adversely affected by decreasingchamber pressure. Still further, highly reactive precursor moleculescontribute to homogeneous gas phase reactions that can produce unwantedparticles which are detrimental to film quality.

[0007] Companies employing the RTCVD process and manufacturers of RTCVDequipment have attempted to address these problems by introducing theconcept of Limited Reaction Processing (LRP) wherein a single substrateis positioned in a reaction chamber and then rapidly heated with the aidof a suitable radiative source to deposit thin films. Rapid heating actsas a reactive switch and offers a much higher degree of controlregarding thickness of films than is possible with some other processes.RTCVD offers advantages over CVD as well in shorter process times,generally lower process costs, and improved process control. At the timeof the present patent application RTCVD is a promising new technique fordeposition of ultra-thin and uniform films. RTCVD is being steadilyintroduced into the commercial arena from the R&D stages by a number ofequipment manufactures.

[0008] Although RTCVD has some clear advantages over general CVD, thereare inherent problems with this technology as well, such as thetemperatures that are used in processing. Larger surfaces require morecritically-controlled temperature, which, if not achieved, can result inwarpage or dislocations in the substrate. Also, the challenge ofproviding a suitable chamber that is contaminant-free and able towithstand high vacuum along with rapid temperature change becomes morecritical with larger surface area requirements.

[0009] Yet another critical area of thin film technology is the abilityof a system to provide a high degree of uniformity and thickness controlover a complex topology inherent in many devices. This phenomena istypically referred to as step coverage. In the case of CVD,step-coverage is better than in line-of-sight physical vapor deposition(PVD) processes, but, in initial stages of deposition there can benon-preferential, simultaneous adsorption of a variety of reactivemolecules leading to discrete nucleation. The nucleated areas (islands)continue to grow laterally and vertically and eventually coalesce toform a continuous film . In the initial stages of deposition such a filmis discontinuous. Other factors, such as mean free path of molecules,critical topological dimensions, and precursor reactivity furthercomplicate processing making it inherently difficult to obtain a highdegree of uniformity with adequate step coverage over complex topologyfor ultra-thin films deposited via CVD. RTCVD has not been demonstratedto be materially better than convention CVD in step coverage.

[0010] ALD, although a slower process than CVD or RTCVD, demonstrates aremarkable ability to maintain ultra-uniform thin deposition layers overcomplex topology. This is at least partially because ALD is not fluxdependent as described earlier with regards to CVD and RTCVD. Thisflux-independent nature of ALD allows processing at lower temperaturesthan with conventional CVD and RTCVD processes.

[0011] ALD processes proceed by chemisorption at the deposition surfaceof the substrate. The technology of ALD is based on concepts of AtomicLayer Epitaxy (ALE) developed in the early 1980s for growing ofpolycrystalline and amorphous films of ZnS and dielectric oxides forelectroluminescent display devices. The technique of ALD is based on theprinciple of the formation of a saturated monolayer of reactiveprecursor molecules by chemisorption. In ALD appropriate reactiveprecursors are alternately pulsed into a deposition chamber. Eachinjection of a reactive precursor is separated by an inert gas purge.Each precursor injection provides a new atomic layer additive toprevious deposited layers to form a uniform layer of solid film Thecycle is repeated to form the desired film thickness.

[0012] A good reference work in the field of Atomic Layer Epitaxy, whichprovides a discussion of the underlying concepts incorporated in ALD, isChapter 14, written by Tuomo Suntola, of the Handbook of Crystal Growth,Vol. 3, edited by D. T. J. Hurle, © 1994 by Elsevier Science B.V.. TheChapter tittle is “Atomic Layer Epitaxy”. This reference is incorporatedherein by reference as background information.

[0013] To further illustrate the general concepts of ALD, attention isdirected to FIG. 1a and FIG. 1b herein. FIG. 1a represents a crosssection of a substrate surface at an early stage in an ALD process forforming a film of materials A and B, which in this example may beconsidered elemental materials. FIG. 1a shows a substrate which may be asubstrate in a stage of fabrication of integrated circuits. A solidlayer of element A is formed over the initial substrate surface. Overthe A layer a layer of element B is applied, and, in the stage ofprocessing shown, there is a top layer of a ligand y. The layers areprovided on the substrate surface by alternatively pulsing a firstprecursor gas Ax and a second precursor gas By into the region of thesurface. Between precursor pulses the process region is exhausted and apulse of purge gas is injected.

[0014]FIG. 1b shows one complete cycle in the alternate pulse processingused to provide the AB solid material in this example. In a cycle afirst pulse of gas Ax is made followed by a transition time of no gasinput. There is then an intermediate pulse of the purge gas, followed byanother transition. Gas By is then pulsed, a transition time follows,and then a purge pulse again. One cycle then incorporates one pulse ofAx and one pulse of BY, each precursor pulse separated by a purge gaspulse.

[0015] As described briefly above, ALD proceeds by chemisorption. Theinitial substrate presents a surface of an active ligand to the processregion. The first gas pulse, in this case Ax, results in a layer of Aand a surface of ligand x. After purge, By is pulsed into the reactionregion. The y ligand reacts with the x ligand, releasing xy, and leavinga surface of y, as shown in FIG. 1a. The process proceeds cycle aftercycle, with each cycle taking about 1 second in this example.

[0016] The unique mechanism of film formation provided by ALD offersseveral advantages over previously discussed technologies. One advantagederives from the flux-independent nature of ALD contributing totransparency of substrate size and simplicity of reactor design andoperation. For example, a 200 mm substrate will receive a uniform layerequal in thickness to one deposited on a 100 mm substrate processed inthe same reactor chamber due to the self-limiting chemisorptionphenomena described above. Further, the area of deposition is largelyindependent of the amount of precursor delivered, once a saturatedmonolayer is formed. This allows for a simple reactor design. Furtherstill, gas dynamics play a relatively minor role in the ALD process,which eases design restrictions. Another distinct advantage of the ALDprocess is avoidance of high reactivity of precursors towardone-another, since chemical species are injected independently into anALD reactor, rather than together. High reactivity, while troublesome inCVD, is exploited to an advantage in ALD. This high reactivity enableslower reaction temperatures and simplifies process chemistrydevelopment. Yet another distinct advantage is that surface reaction bychemisorption contributes to a near-perfect step coverage over complextopography.

[0017] Even though ALD is widely presumed to have the above-describedadvantages for film deposition, ALD has not yet been adapted tocommercial processes in an acceptable way. The reasons have mostly to dowith system aspects and architecture. For example, many beginningdevelopments in ALD systems are taking a batch processor approach. Thisis largely because ALD has an inherently lower deposition rate thancompeting processes such as CVD and RTCVD. By processing severalsubstrates at the same time (in parallel) in a batch reaction chamber,throughput can be increased.

[0018] Unfortunately, batch processing has some inherent disadvantagesas well, and addressing the throughput limitations of ALD by batchprocessing seems to trade one set of problems for another. For example,in batch processor systems cross contamination of substrates in a batchreactor from substrate to substrate and batch-to-batch poses asignificant problem. Batch processing also inhibits process control,process repeatability from substrate to substrate and batch to batch,and precludes solutions for backside deposition. All of these factorsseverely affect overall system maintenance, yield, reliability, andtherefore net throughput and productivity. At the time of this patentapplication, no solutions are known in the industry to correct theseproblems associated with ALD technology as it applies to commercialproduction.

[0019] What is clearly needed is a unique and innovative highproductivity ALD system architecture and gas delivery system allowingmultiple substrates to be processed while still providing attractivethroughput and yield, and at the same time using expensive clean-roomand associated production floor space conservatively. The presentinvention teaches a system approach that will effectively address andovercome the current limitations of ALD technology, leading tocommercial viability for ALD systems.

SUMMARY OF THE INVENTION

[0020] In a preferred embodiment of the present invention an ALDprocessing station for a cluster tool system is provided, comprising aprocessing chamber portion having a lower extremity with a firstcross-sectional area; a base chamber portion below the processingchamber portion, the base chamber portion having a vacuum pumping portand a substrate transfer port, and a second cross-sectional area belowthe circular lower extremity of the processing chamber and the vacuumpumping port greater than the first cross-sectional area; a substratesupport pedestal having an upper substrate support surface with a thirdcross-sectional area less than the first cross-sectional area andadapted to the base chamber portion below the transfer port by a dynamicvacuum seal allowing vertical translation; a vertical-translation drivesystem adapted to translate the substrate support pedestal to place theupper support surface at a processing position substantially even withthe lower extremity of the processing chamber, or at a lower transferposition in the base chamber portion above the pumping port and belowthe transfer port; and a demountable gas supply lid mounted to theprocessing chamber, the lid for providing gases according to an atomiclayer deposition (ALD) protocol. With the substrate support pedestal atthe processing position the cross-sectional area of the substratesupport pedestal and the larger first cross-sectional are of the form afirst pumping passage having a first total effective area determining afist limited pumping speed from the processing chamber portion throughthe vacuum pumping port, and with the substrate support pedestal at thelower transfer position, the cross-sectional area of the substratesupport pedestal and the larger second cross-sectional area form asecond annular pumping passage having a second effective area greaterarea than the first effective area, allowing a second pumping speed fromthe processing chamber greater than the first limited pumping speed.

[0021] In some embodiments the first cross-sectional area is formed by areplaceable ring, thereby allowing the first pumping speed to beincrementally varied by interchanging replaceable rings having constantouter diameter and differing inner diameter. There may also be anannular shroud surrounding a portion of the substrate pedestal beginningat the upper support surface and extending below the upper supportsurface, wherein the pumping area of the annular shroud at the height ofthe upper support surface is substantially equal to the first crosssectional area, such that, with the substrate support pedestal in theprocessing position the annular shroud mates with the firstcross-sectional area constraining all gas flow from the processingchamber to flow within the annular shroud between the annular shroud andthe substrate support pedestal.

[0022] In preferred embodiments the demountable lid closing an upperextremity of the processing chamber is mounted with a demountable seal,such that the lid and the dynamic vacuum seal may be demounted, allowingthe substrate support pedestal to be withdrawn from within the basechamber region upward through the processing chamber region. Thedemountable lid in preferred embodiments comprises a gas distributionsystem for providing processing gases evenly over an exposed surface ofa substrate supported on the substrate support pedestal with thesubstrate support pedestal in the processing position.

[0023] In some cases the substrate support pedestal comprises a closureplate parallel with the upper support surface and forms a vacuumboundary for the processing chamber, a heater plate on the processingchamber side thermally-insulated from the closure plate, and anelectrically-isolated susceptor spaced-apart from and above the heaterplate, the susceptor forming the upper support surface. The heater platemay be a composite heater plate having at least two separately-poweredheating regions, allowing temperature profile across the plate to bemanaged by managing power to the separately-powered regions. In theseaspects the inner heating region is separated from the outer heatingregion by at least one groove substantially through the heater plate. Ina preferred embodiment the inner heating region has a cross-sectionalare substantially equal to the cross-sectional area of a substrate to beheated by the heater plate. In some preferred cases the dynamic vacuumseal is a stainless steel bellows.

[0024] The present invention in its various embodiments provides aflexible and effective way t accomplish ALD processing on semiconductorwafers, and the various aspects of the invention are taught below inenabling detail.

BRIEF DESCRIPTION OF THE DRAWINGS

[0025]FIG. 1a is a schematic illustration of a generic atomic layerdeposition process.

[0026]FIG. 1b is a typical timing diagram for ALD gas pulsing.

[0027]FIG. 2 is an isometric view of a low-profile compact reactor unitaccording to an embodiment of the present invention.

[0028]FIG. 3a is an isometric view of the compact reactor unit of FIG. 1showing a flap-type gate valve and flange according to an embodiment ofthe present invention.

[0029]FIG. 3b is a right side view of two compact reactor units as shownin FIG. 1 according to an embodiment of the present invention.

[0030]FIG. 4 is an elevation view of VESCAR 27 integrated with aload-lock according to yet another embodiment of the present invention.

[0031]FIG. 5 is an elevation view of an ALD vertically-stacked systemarchitecture according to an embodiment of the present invention.

[0032]FIG. 6 is a plan view of an LP-CAR according to an embodiment ofthe present invention adapted for processing multiple substrates in asingle LP-CAR unit.

[0033]FIG. 7 is a top view of production system 19 according to analternate embodiment of the present invention.

[0034]FIG. 8 is an elevation view of the stacked compact reactor unit ofFIG. 1 viewed from the rear according to an embodiment of the presentinvention.

[0035]FIG. 9 is a diagram of a gas recycling and precursor trappingsystem according to an embodiment of the present invention.

[0036]FIG. 10A is an idealized plan view of a cluster-tool-basedprocessing system as known in the art, and as used in embodiments of thepresent invention.

[0037]FIG. 10B is a cross-section elevation view, mostly diagrammatical,of a conventional CVD processing station as known in the art.

[0038]FIG. 11A is an isometric view of a multipurpose processing stationaccording to a preferred embodiment of the present invention.

[0039]FIG. 11B is an exploded view of the multipurpose processingchamber of FIG. 11A.

[0040]FIG. 11C is an isometric, cutaway elevation view of themultipurpose processing station apparatus of FIG. 11A.

[0041]FIG. 11D is an elevation section view of the multipurposeprocessing chamber of FIG. 11A, shown in processing mode.

[0042]FIG. 11E is an elevation section view of the apparatus of FIG. 11Ashown in transfer mode.

[0043]FIG. 12 is an elevation section view through a pedestal element,including an electrical feedthrough apparatus, from FIG. 11E.

[0044]FIG. 13A is an elevation cross-section of the electricalfeedthrough apparatus of FIG. 12.

[0045]FIG. 13B is a section view taken through a body assembly of thefeedthrough of FIG. 13A, taken along section line 13B-13B of FIG. 13C.

[0046]FIG. 13C is a top view of the feedthrough apparatus of FIG. 13A.

[0047]FIG. 14A is a side elevation view of a ceramic insulator barrierfrom FIG. 12.

[0048]FIG. 14B is a plan view of the insulation barrier shown in sideview in FIG. 14A.

[0049]FIG. 15A is an isometric view of a two-zone heater plate in anembodiment of the present invention.

[0050]FIG. 15B is a plan view of the heater plate of FIG. 15A.

[0051]FIG. 15C is side view of the heater plate of FIG. 15A.

[0052]FIG. 16A is an isometric view a connector post in an embodiment ofthe present invention.

[0053]FIG. 16B is an end view of the connector post of FIG. 16A.

[0054]FIG. 16C is a section view of the connector post of FIG. 16A andFIG. 16B.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An Atomic Layer DepositionSystem Using Individual, Stackable Modules

[0055] In contemplating commercialization of atomic layer depositiontechnology, batch-type ALD systems, meaning systems generally whereinsubstrates to be coated are arranged in different planes, and whereinrelatively large numbers of substrates are coated in a single reactorsimultaneously, have been seen as attractive from the point of view ofthroughput, but these sorts of large batch systems are seen by thepresent inventors to have several serious drawbacks compared to acompact low-profile system having a single gas presentation path, astaught in several embodiments below. Among these difficulties are:

[0056] (a) Gas pulsing in a batch system cannot be as rapid and as sharpas may be done in a compact single substrate system.

[0057] (b) Backside deposition is difficult to prevent inmulti-substrate systems. To prevent backside deposition individualsubstrates need to be clamped on a dedicated heater, including suchapparatus as electrostatic chucks.

[0058] (c) Plasma cleaning has been found to be ineffective in largebatch systems, as compared to single substrate systems. In situ plasmacleans allow the realization of a very long time between maintenancecleaning.

[0059] (d) Gas depletion effects can be a severe process limitation inbatch process reactors and are difficult to address in batch systems.

[0060] (e) Batch processors are less flexible than single substratesystems for process control, substrate-to-substrate repeatability,process variation, and maintenance. Batch processors also cannot beeasily matched to relatively small footprint clustering architectureconfigurations.

[0061] For these and other reasons the present inventors have developeda unique approach to ALD processing comprising a low-profile compact ALDreactor (LP-CAR), which reduces both internal volume and externalheight, and allows for fast gas switching and enhanced process control,as well as for a unique system architecture. The unique architectureenabled comprises a vertically-stacked multi-unit system, adaptable toclustering schemes for serial integration.

[0062] In embodiments described below, the inventors teach a uniquelow-profile compact reactor, and unique system architectures for use ofthe ALD reactor in production, which addresses and solves limitingfeatures of batch-types ALD systems.

[0063] In the unique design of the LP-CAR in embodiments of the presentinvention, high throughput is enhanced through fast gas switchingpromoted in part by minimized internal process volume of the reactorrelative to the surface area presented to be coated in the reactor.While length and width of a single-substrate reactor are dictated by themaximum substrate size to be accommodated, typically at about 1.5 timesthe substrate diameter (if the substrate is round), the internal heightof the reactor is the controlling dimension for internal volume. Inembodiments of the invention herein, the inventors have also recognizedan advantage of having a single, unimpeded gas presentation path tosubstrate surface to be coated, which generally calls for surface to becoated to presented in a common plane.

[0064] Boundary layer conditions and proper gas flow must be achieved,and it is desirable to have alternative plasma lid designs. The ALDprocess also requires a substrate heater in the process volume to heatsubstrates during processing, and additionally there are specificrequirements for gas delivery and gas exhaust subsystems. Given all ofthese requirements, in embodiments of the present invention, alow-profile, compact ALD reactor (LP-CAR) suitable for single substrateprocessing is provided. In embodiments of the present inventiondescribed below, low-profile is defined as the height of a reactor asopposed to horizontal dimensions. The ratio of height of an LP-CAR tohorizontal dimensions in different embodiments of the invention canvary, depending on specific system requirements. The ratio of height tohorizontal dimensions, however, in embodiments to follow is typicallyless than 1, and can be as low as 0.2. A ratio of about 0.65 is morecommon for embodiments described herein.

[0065] In embodiments of the invention the LP-CARS areindependently-controllable reactors, and may be used as building blocksin a unique architecture to address throughput requirements anddesirable flexibility in processing sequence. LP-CARS in preferredsystem embodiments are vertically stacked, which promotes efficient useof precious process real estate. The vertically-stacked architecture istermed by the inventors VESCAR™ for vertically-stacked compact ALDreactor.

[0066] In some embodiments taught in enabling detail below, the VESCARsystem can be a stand-alone configuration, wherein substrates areprovided to and accepted from the VECAR unit through a cassetteload-lock subsystem. In other embodiments one or more load locks and oneor more VESCAR units are interfaced to a cluster tool handling system,which may also comprise processing subsystems other than ALD, such aCVD, PVD, cleaning, lithography, and others.

[0067]FIG. 2 is a mostly diagrammatical isometric view of a compactreactor unit 33 according to an embodiment of the present invention,having substrate surface to be coated presented in substantially asingle plane, and a single gas flow path to the substrate surface. Asubstrate I/O (in/out) opening 53 on one side of the reactor unit in apreferred embodiment of the invention is equipped with a gate valve, asdescribed above, and as is described more fully below.

[0068] Gas flow over a loaded substrate 45 in position to be processedis in a horizontal direction substantially parallel to the surface ofsubstrate 45 upon which deposition is to take place, entering from oneside (gas in) and exiting an opposite side (gas out). Precursors(chemical species) are alternately pulsed into reactor unit 33 followedby a gas purge, as described relative to FIG. 1b above. In thisembodiment the gas flow is from right (gas in) to left (gas out) asrepresented by directional arrows in the figure. In another embodimentthe gas flow may be from left to right In one embodiment the individualcompact reactor has an inlet and an exhaust manifold built into thereactor body.

[0069] Compact reactor unit 33 may be constructed from any suitablematerial known in the art such as stainless steel, aluminum, compositegraphite, or other materials deemed appropriate for sustaining anapplied vacuum and providing suitable characteristics as known in theart for deposition chambers. In one embodiment, reactor unit 33 may bereinforced with structural ribs for the purpose of adding strength undervacuum.

[0070] Compact reactor unit 33 in the embodiment shown has an overallheight h and is of a width and depth so as to accommodate at least asingle substrate for deposition. Scaling may be done for substrates ofdifferent sizes, from very small up to as much as 400 mm. Diameter ormore.

[0071] The actual height of the substrate hold area 49 expressed ash_(i), in terms of the horizontal dimensions, is a is a very importantparameter, as this height helps define the internal volume of a reactorwherein gas pulsing and processing takes place. The external height iscontrolled to provide a low-profile to facilitate stacking of reactors,as briefly described above, in a system architecture to be describedfully below. The internal height of the reaction region in an LP-CARunit according to embodiments of the present invention is separatelycontrolled to provide a practical minimal volume relative to substratesurface area to be coated, which maximizes gas utilization and enhancesfast gas switching. In more general terms, the critical issue discoveredby the present inventors is that speed of gas delivery to the surface tobe coated must be maximized, while providing a sufficient quantity ofprecursor to assure surface saturation, and without an overabundance ofgas. This is best accomplished by a reactor internal shape whichpromotes a uniform cross section in the wave front of advancing gasinjected into the reactor, minimizes internal volume, and provides asufficient clearance in the gas path over the surface to be coated thatgas flow to the substrate surface is not impeded.

[0072] In an LP-CAR provided for a substrate diameter of 300 mm., theinternal height in embodiments of the invention will preferably be aboutone inch, but can vary somewhat from one embodiment to another. It ispreferred by the inventors that the ratio of internal height tohorizontal internal dimensions of the reaction region not exceed about0.25, to insure fast gas switching and efficient precursor utilization.

[0073] Retractable substrate lift pins (not shown) in some embodimentsare positioned in the bottom surface of substrate hold area 49 for thepurpose of supporting the substrate. The number of substrate-lift pinspresent in substrate hold area 49 is typically three or more and thepins are arranged in a pattern to support the substrate horizontally.

[0074] Substrate-lift pins are commonly used for horizontal support of asubstrate in a reactor chambers in processes such as RTCVD. In someembodiments, substrate-lift pins are part of a substrate holding tray.In other embodiments, substrate-lift pins are built in to the reactorchamber. Typically, substrate-lift pins come to a point at the substratesurface for the purpose of providing a small heat-sink area and to avoidsurface coating anomalies. This rule is more critical in processes thatuse more heat such as RTCVD, and or in cases where a substrate isprocessed on both surfaces simultaneously. In some embodiments a flatelectrostatic chuck (ESC) with suitable heat capabilities may be used tosecure substrates during processing, precluding backside deposition.

[0075] Compact reactor unit 33 is heated and cooled during substrateprocessing. Area 51 represents a heater compartment wherein a heatingdevice such as a resistance-heated coil is housed. Area 47 comprisescooling lines running through the top surface of reactor unit 33. Itwill be apparent to one with skill in the art that differing chemicalspecies or precursors that are used in various processes may requiredifferent temperatures to be maintained inside compact reactor unit 33during process. Therefore it is intended by the inventors that variousheating and cooling methods known in the art of deposition be applicablein various embodiments of the present invention. Similarly, area 51 mayhouse more than one type of heating element as may be required fordelivering levels of heat in differing measures of time, as may berequired, for example, to do in-situ annealing, and so on.

[0076]FIG. 3a is a simplified isometric view of the compact reactor unit33 of FIG. 2 according to an embodiment of the present invention whereina flap-type remotely-operable valve 52 is provided to cover and exposeopening 53. This valve is closed for processing and open for substratetransfer to and from the LP-CAR. There is in this embodiment a vacuumseal 46 surrounding opening 53, which may be an o-ring in someembodiments, a quad-ring, a metal seal, or other vacuum seal as known inthe art. Valve 52 is provided to close against the vacuum seal toisolate the unit in operation. A flange 54 in one embodiment ispositioned behind gate valve 52 and also has a vacuum seal 48 providedfor sealing against a non-vacuum side of an interface wall of a vacuumchamber in a production architecture to be described in further detailbelow.

[0077] There are various methods that are known in the art for automaticcontrol of gate valves, such as valve 52. In a preferred embodiment ofthe present invention the gate is a flap-type valve, and a cam-operatedelectrical mechanism (not shown) is provided and mounted to a wall ofreactor unit 33 and also to a pivot arm (not shown) on the valve door.Electrical leads pass through the body of reactor 33 from the non-vacuumside in operation. A variety of mounting schemes may be implemented formounting a cam-type device for opening and closing gate valve 52 withoutdeparting from the spirit and scope of the present invention.Electrically-operated cam devices are common and known in the art aswell as to the inventors.

[0078] The embodiment represented here is but one example of how LP-CAR33 may be provided with a gate valve for the I/O opening.. In anotherembodiment a flap-type door may be provided pivoted from above ratherthan from below. In yet another embodiment, instead of a flap-type door,a cam-operated sliding door may be incorporated. In a preferredembodiment, a flap-type door is used because of simplicity of design andimplementation.

[0079] It will be apparent to one with skill in the art that the actualshape of flange 54 as well as gate valve 52 may vary considerablywithout departing from the spirit and scope of the present invention.For example, flange 54 may be of the form of a rounded rectangle orperhaps an elliptical shape. Similarly, gate valve 52 may take otherforms than those described above. In some embodiments a sealinginterface may be provided without using a flange as an integral part ofthe reactor body.

[0080]FIG. 3b is a side elevation view of two compact reactor units asdescribed in FIG. 3a according to an embodiment of the presentinvention, illustrating a vacuum interface that is formed with flange 54and an interfacing wall 42 of a vacuum chamber. On the non-vacuum side astacking fixture or rack (not shown in FIG. 3b) is used to supportreactor units 33 a and 33 b and other reactor units not shown in FIG. 3bthat may be a part of a VESCAR system according to embodiments of thepresent invention. It will be apparent to one with skill in the art thata stacking fixture or rack used for supporting and spacing reactor unitsin a vertical configuration may be constructed from any durable materialsuch as stainless steel, or any other suitable material as long as itcan support the individual reactor units and resist dimensional changesthat may occur. Fixtures used for positioning one or more components tobe interfaced to a shared interface in a system are relatively commonand known by persons skilled in the art. The important characteristicsfor a stacking fixture as in this embodiment of the present inventionare that it can equally and accurately space the reactor units,facilitating successful and repeatable transfers of substrates, and thatit can support the weight. In one embodiment a fixture in the form of arack having removable spacers for proper positioning could be used. Inanother embodiment, accurate spacing may be accomplished via adjustingscrews and the like.

[0081] In various embodiments spacing of the LP-CAR units in a verticalstack must allow for providing thermal isolation between the lower hotregion of each reactor and the upper cool region of each adjacentreactor. Similarly, the topmost and the lowermost LP-CAR in a stackshould have a similar thermal environment to the other reactors in astack.

[0082] The area to the left of chamber wall 42 shown in FIG. 3b is thevacuum region of a vacuum transfer chamber in a vertically-stackedsystem described below. Securing flange 54 to the chamber wall can beaccomplished by conventional fastening techniques and hardware, such assocket-head screws. In an alternative embodiment, a mating flange may beaffixed to the chamber wall, perhaps via welding, so that flange 54could be clamped to the mating flange thereby completing the interface.In such a case the mating flange may have alignment pins that fit intoopenings present in flange 54. It will be apparent to one with skill inthe art that there are many configurations possible only some of whichare described herein.

[0083]FIG. 4 is an elevation view of a VESCAR system 27 interfaceddirectly to a cassette load lock 21 in a production system embodiment ofthe present invention. In this embodiment, pre-processed substrates areloaded into cassette load lock. In this architecture a wall separating aclean room environment from a process room has an opening through whichcassette load lock 21 and VESCAR unit 27 are interfaced This sort ofclean room interfacing is well-known in the art for production systems,to conserve precious clean room space.

[0084] VESCAR system 27 comprises a vacuum handling chamber 32 with wall42 (see also FIG. 3b) and a Z-axis robot 31 with horizontal as well asvertical extension capabilities, and is shown here extending intocassette load lock 21. A cassette 79 loaded with preprocessed substratesis positioned so that Z-axis robot 31 can pick up a substrate and movethe substrate into VESCAR unit 27. Once inside VESCAR 27, Z-axis robot31 rotates 180 degrees extends to the proper vertical position forplacement of a substrate into a reactor unit, of which 10(a-j) are shownin a vertically stacked architecture interfaced to vacuum wall 42.

[0085] Ten LP-CAR units, one-above-another as shown in FIG. 4 isconsidered by the inventors a practical number to address throughputneeds while at the same time conserving real estate. In some embodimentsof the present invention there are more than one extension and transferarm associated with Z-axis robot 31, and/or more than one end effectorto avoid any transfer limitations on throughput. Finished substrates areunloaded in reverse order to the loading process described, and thefinished substrates are placed back in cassette 79.

[0086] The VESCAR architecture of FIG. 4 is a minimum-cost solution, anda starting point for further integration into more sophisticated VESCARarchitectures. Also, the architecture shown is a good process researchand development configuration for use in developing process sequencesand the like using multiple LP-CAR units. Processes developed in theVESCAR system of FIG. 4 may be scaled up to more sophisticatedprocessing schemes to be described below.

[0087]FIG. 5 is an elevation view of an ALD production system 19according to an embodiment of the present invention. The uniquecombination and automation of various components described hereineffectively surmount obstacles related to system architectures availablewith more conventional ALD reactors. Embodiments described and taughtbelow provide substantive solutions to problems such as slow depositionrate, use of scarce production space, and other problems faced withcurrent ALD applications and competing processes.

[0088] Referring now to FIG. 5, a (VESCAR) 27 comprises a vacuum chamber32 having a vertical interface for the attachment of separate compactreactor units 33 a-j, as also described above with reference to FIG. 4.Compact reactor units 33 a-j are adapted to sustain suitable vacuum bothseparately and in integration with vacuum chamber 32. A flap-type gatevalve present in each compact reactor unit 33 a-j allows for separatepump-down (gate closed) and sharing vacuum in vacuum chamber 32 (gateopen). Individual provision at each reactor unit allows for vacuum,purge, and flow of process gases, and suitable valving, including theload and unload flap-type valve described above, allows substrates to betransferred to and from the vertically-stacked reactors to and fromchamber 32.

[0089] It will also be apparent to one with skill in the art that theremay be more or fewer compact reactor units stacked vertically andpresent in VESCAR 27 than the number shown in FIGS. 4 and 5 withoutdeparting from the spirit and scope of the invention. In the embodimentdescribed here with reference to FIG. 5, there are 10 compact reactorunits 33 a-j, however, in actual practice of the present invention, asmany compact reactor units may be incorporated into VESCAR 27 as may bedeemed appropriate for facilitating a high throughput in a competitivemanner with respect to known commercial processes. The number is limitedas a practical matter by vertical space available, and must be matchedby the range of handling equipment dedicated to the purpose.

[0090] Z-axis robot 31 is provided in chamber 32 for the automatedloading and unloading of substrates with respect to compact reactorunits 33 a-j, and for interfacing with other material-handlingequipment. Z-axis robot 31 can extend to vertical and horizontalpositions and is programmed to interface with each compact reactor unit33 a-j. Z-axis robot 31 can also be programmed in this embodiment toload substrates to reactors in any sequence desired. For example,substrates can be loaded from bottom to top, from top to bottom, frommiddle to top, and so on. Further, substrates can be unloaded from onecompact reactor unit and reloaded to another compact reactor unit. Anysequence is possible. In some embodiments there are multiple substratehandling devices, such as end-effectors and the like, associated with asingle Z-axis robot.

[0091] Compact reactor units 33 a-j are interfaced to chamber 32 alongone wall of the chamber, and carefully spaced to allow for error-freeloading and unloading by the Z-axis robot. The reactors interface to thechamber with a vacuum seal, and are supported by a rack assembly outsidechamber 32, as is illustrated below in additional detail with referenceto further drawing figures.

[0092] In this embodiment a vacuum central robotic substrate handler 23is interfaced with VESCAR 27 via a gate valve 29. Gate valve 29 is avacuum valve that allows VESCAR unit 27 to be isolated from thecluster-tool handler between substrate transfers. A transfer mechanism43 operated through a rotary mechanism 25 loads and unloads substratesto and from Z-axis robot 31. Transfer mechanism 43 in FIG. 1 is shownextended to gate valve 29. In a position 180 degrees from the positionshown, transfer mechanism 43 can extend to a cassette load lock 21 wherepreprocessed substrates are loaded and finished substrates are unloaded.Robotic substrate handling systems of the sort depicted by handler 23are commercially available from several vendors; among them BrooksAutomation, Equipe, and Smart Machines.

[0093] In a preferred embodiment of the present invention, preprocessedsubstrates are first placed into cassette load lock 21 in a verticallyoriented cassette or rack (not shown). After the preprocessed substratesare presented in cassette load lock 21, the lock is closed and evacuatedto a specified vacuum through a vacuum port (not shown). The transfervolume within robotic handler 23 is also evacuated to a specified vacuumthrough a vacuum port also not shown. Vacuum chamber 32 is pumped downthrough a similar vacuum port (not shown). With all units suitablepumped, a gate valve 35 opens to allow transfer mechanism 43 to extendinto cassette load lock 21 to retrieve substrates one-at-a-time. Acassette handler (not shown) in cassette load lock 21 can raise or lowera platform which holds a vertical cassette holding the preprocessedsubstrates.

[0094] When transfer mechanism 43 retrieves a substrate, it thenretracts to within the robotic handler volume and rotates to a 180degree position so that it may extend to VESCAR 27. Typically gate 35closes between transfers, but this is not strictly required in manyprocess-flow schemes. With the transfer mechanism at VESCAR 27, gatevalve 29 opens to allow transfer mechanism 43 to pass the substratethrough to Z-axis robot 31. Z-axis robot 31 then receives and loads thesubstrate into one or another of the vertically-stacked compact reactorunits, and so on.

[0095] Many operating schemes are possible. In the architecture shownone preferred scheme is to adapt the system with an equal number ofcompact ALD reactors as positions in a load-unload cassette 21. Transfercontinues until all substrates from load lock 21 are transferred toreactor units (all reactor units then having each a substrate to becoated), then intervening valves close, and processing commences inreactor units 33 a-j. This system has the processing steps of a batchsystem while all substrates are processed in individually-isolatedreactor units

[0096] Many other schemes are possible. Because each compact reactor hasan isolation gate valve, in some schemes reactor processing commences assoon as a substrate is loaded. Other process flow schemes will beapparent to those with skill in the art.

[0097] In one embodiment, as individual pumping and isolation isprovided for chamber 32, at the time that reactors are loaded and beforeprocessing begins in the reactor units, pressure is increased in chamber32, by bleeding in an inert gas, to a level sufficient to provide apressure differential across the flap-type valves of the individualreactors, proving additional sealing force to the individual reactorvalves than would otherwise be possible.

[0098] After all of the processes have been performed in compact reactorunits 33 a-j, flap type gate valves (FIG. 3a element 52) installed ineach unit can be opened to allow substrates to be unloaded in a reverseprocess from that described above with reference to loading. One by one,finished substrates are returned typically to the same cassette fromwhence the substrates were retrieved. Lock 21 may then be vented withvalve 35 closed, and a cassette load of finished substrates may beremoved.. This processing is wholly automated from the point of leavingthe preprocessed substrates in cassette load lock 21 to picking up thefinished substrates in cassette load lock 21. Timing features related togate valve opening, speed of delivery, length of process or processes(including sequence of processes), pump down sequences, and otherrequired commands are programmable functions of controlling software andhardware according to techniques generally known in the art.

[0099] Due in part to the flux-independent nature of the ALD process,wherein layers are formed on the deposition surface by chemisorption asdescribed above, and as is known in the art, compact reactor units suchas compact reactor units 33 a-j can be designed so as to have a widththat will receive substrates of optimum size such as 300 mm substrates.Also, smaller substrates could be processed in the same system withoutscaling down the size of compact reactor units 33 a-j. In anotherembodiment, a scaled-down system could be implemented for the purpose ofprocessing smaller substrates one-at-a-time, or a scaled-up versioncould be provided for other products such as flat panel displays and soon.

[0100] In some embodiments of the present invention, an LP-CAR developedfor a particular substrate size, as mentioned in the paragraph justabove, may be adapted for processing multiple substrates of smallersize. FIG. 6 is a plan view of an LP-CAR 33 of the type shown in FIG. 3awith the nominal substrate size shown as a dotted circle 70. An LP-CARunit in alternative embodiments of the invention may be adapted toprocess, for example, three substrates 72 smaller than substrate 70 inLP-CAR unit 33. In some embodiments unit 33 may be provided with arotary chuck so substrates 72 may be placed and retrieved at a commontransfer point. In other embodiments the robotic transfer devices may beadapted to place the substrates at the desired locations on a hearth. Inyet other embodiments multiple substrates may be handled in a commoncarrier transferred to and from an LP-CAR unit. This allows for use ofthe single-substrate LP-CAR design with multiple substrates in the sameprocess plane.

[0101] The unique architecture described above provides a whollyautomated commercial ALD process not previously available with currentart. By utilizing VESCAR 27, a high process throughput can beaccomplished comparable to throughput provided with competingtechnologies such as CVD, PECVD, and the like. Also, because of theinherent uniformity improvements attainable through the ALD process, andthe fact that separate reactor units are used in place of batchtechnology, higher yields can be realized without the problemsassociated with cross contamination and the like. And in achieving theseadvantages, scarce production floor space is used very conservatively,due to the vertical stacking of compact units.

[0102] The embodiment described with the aid of FIG. 5 represents butone example of many possible arrangements of equipment that could beutilized with VESCAR 27. While there is only one cassette load lock 21and one VESCAR 27 shown in this embodiment, there are two additionalpositions on robotic handler 23 to which additional load locks or VESCARunits may added. Further detail regarding the addition of equipment asdescribed above will be provided in an additional embodiments below.

[0103]FIG. 7 is a top view of production system 19 of FIG. 5 accordingto an alternative embodiment of the present invention wherein additionalVESCAR units or cassette load locks may be interfaced with robotichandler 23 for the purpose of running additional processes, such as CVD,cleaning, and the like. Robotic handler 23 has four 90 degree positionsillustrated as positions A, B, C, and D in FIG. 7. Position A isconnected to gate valve 35 and cassette load lock 21 also described withreference to FIG. 5. Position B is connected to a gate valve 75 and acassette load lock 71. Position C is connected to gate valve 29 andVESCAR unit 27 also described with reference to FIG. 1. Position D isconnected to a gate valve 77 and a second VESCAR unit 73. Transfermechanism 43 is controlled by operating unit 25 of FIG. 5 wherebytransfer mechanism 43 is rotated to achieve each position. In FIG. 7mechanism 43 is shown extended at position C with a loaded substrate ina position to be received in VESCAR unit 27. Gate valve 29 is in openposition allowing transfer of the substrate. Transfer mechanism 43 isalso shown in a retracted position (illustrated by dotted lines) andoriented to gate valve 75 and cassette load lock 71 in position B. Inthis example the transfer mechanism has taken a substrate from cassetteload lock 71 and placed it in VESCAR unit 27. Transfer mechanism 43operates in a like fashion with respect to all four positionsillustrated in that extension, retraction, rotation and extension areperformed in order to successfully transfer substrates from load locksto VESCAR units and back to load locks.

[0104] In one embodiment, three VESCAR units and one cassette load lockmay be utilized wherein different parallel processes (all reactor unitsin one process module dedicated to one process) are being performed ineach process module. Similarly, serial processing (each reactor unit inone process module dedicated to a different process) can also beperformed. In another embodiment, one process module may be dedicated toserial processing whereas another process module is dedicated toparallel processing with the system incorporating two cassette loadlocks. It will be apparent to one with skill in the art that there aremany processing configurations that could be utilized in productionsystem 19 without departing from the spirit and scope of the presentinvention several of which have already been described above.

[0105]FIG. 8 is a rear view of VESCAR system 27 showing three of the tenvertically stacked reactor units interfaced to chamber wall 42 accordingto an embodiment of the present invention. A vertically-oriented gasinlet manifold 55 is shown on one side of the vertically-stacked reactorunits for providing a gas or vapor material to the reactors. In apreferred embodiment of the present invention, multiple precursors andinert gases may be alternately pulsed into reactor unit 33 duringprocessing, but only one manifold 55 is shown in this figure to avoidconfusion in the drawing. In actual practice of the present inventionone manifold is used for each precursor gas or vapor and at least onefor purge gas. Therefore, a minimum of three manifolds would typicallybe used.

[0106] In a preferred embodiment of the invention a valved charge tubeis used to control quantity of supply to each reactor for each gas orvapor provided. In FIG. 8 one such charge tube 62 is shown. Theseseparate charge tubes are of a predetermined volume and are charged withgas or vapor of controlled pressure and temperature so the number ofmolecules of gas or vapor is known Each charge tube is isolated by twovalves, which, in the case of tube 62 are charge valve 54, and injectionvalve 61. Upon opening injection valve 61, the charged content of thatsection of tubing is discharged into reactor unit 33. Opening chargevalve 54 with injection valve 61 closed allows the charge tube to befilled with a precursor gas, vapor, or purge gas at a predeterminedpressure and temperature.

[0107] A quick-connect flange 56 is used to connect the gas andprecursor source to reactor unit 33, and other quick connects may beprovided to allow for relatively quick release of all gas and vaporlines to and from each reactor unit.. The pulsing of precursors and gaspurging is done in a sequential manner as required for an ALD sequence.The time of individual pulses is typically very short (approximately 50to 300 milliseconds depending on the process), and pulses are typicallyseparated by a short transition time. For this reason valves of a fastswitching nature are incorporated. Fast switching valves are well knownin the art and to the inventors.

[0108] A vertically-oriented vacuum exhaust manifold 63 is connected tothe right side of reactor unit 33 in this embodiment via a quick connectfitting 58 for the purpose of exhausting gases and vapors from thereactor chambers. The use of quick connects is meant to facilitateremoval and service of individual reactors. Quick connects, as such, areknown in the art and are available in a variety of shapes andconfigurations. A vacuum shut off valve 60 is provided for facilitatingrepair or replacement. This valve will be typically open during gaspulsing.

[0109] Power is provided to reactor units 33 via representativeelectrical lines 57. Power is provided for powering various elementssuch as gate valve 52 of FIG. 3B, heating sources and the like. Controlsignals are provided for such as valves and are provided viarepresentative control lines 59. Electrical connectors 67 and 68 areprovided in electrical lines such as lines 57 and 59 for the purpose offacilitating quick removal of reactor unit 33.

[0110] As described with reference to FIG. 2, substrates typically mustbe heated during processing and cooled after processing. Therefore,connections are also provided for liquid cooling. Cooling systems thatrecycle coolant are common in cooling reactors. Such systems are knownin the art and to the inventors.

[0111] A heat source is built into reactor 33, and, in embodiments ofthe present invention the heater is constrained in height to accommodateunique overall low-profile requirements for the CAR unit..

[0112] In a preferred embodiment of the present invention, one vacuumpump can pump down all or any number of compact reactor units 33. Thisis accomplished with a vacuum interface installed between the vacuumpump and reactor units to which all vacuum lines leading from reactorunits are connected. At each connection, a valve is presented that canopen and close per programmed instruction so that any combination ofreactor units can be pumped down simultaneously or separately. In apreferred embodiment, one or more reactor units could be brought toambient Nitrogen or air, and isolated by closing valves 60 and 61,leaving other units under vacuum and so on.

[0113] In a preferred embodiment of the present invention individualcompact reactor units can be easily removed from the interfacing wall ofvacuum chamber 32 of FIG. 5 by disconnecting quick connects, unpluggingelectrical wires, uncoupling flange 54 from the interfacing chamberwall, and removing reactor unit 33 from the stacking fixture or rackused for positioning and support. A flange plug (solid flange witho-ring) in some instances is provided to be bolted or clamped to achamber wall or mating flange so that a number of reactor units might beremoved for maintenance and so on without requiring a complete shut downof the system or replacement with other LP-CAR units.

[0114] It will be apparent to one with skill in the art that there are anumber of quick connects that could be used to facilitate easy removalof a reactor unit without departing from the spirit and scope of thepresent invention. These methods and such hardware are known in the artand to the inventors.

[0115]FIG. 9 is a diagram of a gas recycling and precursor trappingsystem according to an embodiment of the present invention, wherein gascan be recycled and harmful byproducts can be trapped for disposal.Because precursors and gas purges are separately pulsed into compactreactor units 33 as described above, it follows that precursors orbyproducts may be collected and trapped separately. Recycling andtrapping system 65 is installed on the exhaust side of each reactor witha closed loop control connecting a three way fast-switching pneumaticvalve with gas inlet manifold 55 of FIG. 4 so that purge gas P may berecycled back into reactor unit 33. Chemical species, represented by Aand B, can be trapped separately in a precursor trap 69 (i.e. Acryo-trap) that can be removed for the purpose of disposing of harmfulelements. Non-hazardous gases or chemicals may bypass precursor trap 69and be pumped out by the exhaust pump. The innovative approach describedand taught herein enables the usage of gas to be reduced and provides amore environmentally friendly process.

[0116] It will be apparent to the skilled artisan that in the case ofserial processing, each reactor would have a trap system such as trapsystem 65 as described above. However, with parallel processing, wherethe same process is being performed in each reactor, then one trapsystem may be utilized on the exhaust side.

[0117] It will be apparent to one with skill in the art that aproduction system such as production system 19 of FIG. 5 may be utilizedand integrated with a variety of technologies without departing from thespirit and scope of the present invention. For example, VESCAR unit 27may share the robotic handler's platform interface with a CVD system, acleaning module, a lithography unit, or other process unit known in theart. It will also be apparent to one with skill in the art that becauseof the uniformity characteristics inherent with the ALD process throughchemisorption, there are no substrate size limitations or reactor numberlimitations. Therefore VESCAR unit 27 may be designed for optimumcommercial application with respect to other competing technologies.There are many other configuration and application embodiments that arepossible, many of which have already been described.

A Universal Chamber for use with a Cluster Tool System

[0118]FIG. 10A is a mostly diagrammatical plan view of acluster-tool-based processing system as used both in the prior art andin practicing the present invention. The cluster tool itself is amaterial handling system operating substantially within a vacuum chamber1101. A wafer transfer apparatus 1103 is positioned to operate from thecenter of the vacuum chamber, and is adapted to place and retrieve, byrotation and extension, substrates, typically semiconductor wafers in ICmanufacturing sequences, from and to processing station appended atpoints around the periphery of substantially circular vacuum transferchamber 1101.

[0119] In the system shown there are 6 station positions numbered 1through 6, and each of these stations is adapted to chamber 1101 by amounting flange and slit valve arrangement 1102. In this scheme twostations, 5 and 6, are used as airlocks for bringing wafers into and outof chamber 1101, which is held under high vacuum by pumping apparatusnot shown, and the remaining four stations 1-4 are available forprocessing.

[0120] Wafers are moved from outside into chamber 1101 through load-lock1104, then typically sequentially through the four processing stations,and back to outside through unload lock 1105. It is not necessary,however, that the wafers move sequentially through the four processingstations, as transfer apparatus 1103 is capable of placing andretrieving in any desired order.

[0121]FIG. 10B is a cross-section elevation view of station 1106 of FIG.10A, showing some additional typical features of such a processingstation. Station 1106 is based on a sealable process chamber interfacingto chamber 1101 of FIG. 10A through flanged slit valve apparatus 1102.It is through this interface that wafers are brought into chamber 1107for processing, and removed from chamber 1107 after processing. Chamber1107 has a vacuum pumping port 1109, through which the chamber isevacuated, and a heatable hearth 1110 for supporting a wafer 1111 duringprocessing. Gases used in processing are introduced from a gas feed andcontrol unit 1115 through conduit(s) 1114 via ring manifold 1113 andshowerhead manifold 1112.

[0122] In the system of FIG. 10A, chamber 1101 is pumped by substantialvacuum pumps at all times to keep all of the volume in the chamber underhigh vacuum. The purpose is to avoid contamination by atmospheric gasesbetween processing stations. Wafers to be processed are placed inload-lock chamber 1104, typically in a carrier, and the load-lock isevacuated to a vacuum level on the order of the vacuum level in chamber1101. An inner valve is then opened, and wafers may then be retrievedfrom the load-lock by transfer apparatus 1103 and transferred to any oneof processing stations 1-4.

[0123] Typically during processing in one of the processing stations,vacuum pumping is throttled to control process chamber pressure withoutusing excessive quantities of process gases. Such throttling may beaccomplished in a number of ways, including valves having controllableopenings. In a typical process cycle, after processing is complete,gases are valved off in unit 1115 (FIG. 10B), and the throttlingmechanism is opened to allow maximum pumping speed in the processingchamber. The purpose is to reduce the gas pressure in the processingchamber to a value close to that in transfer chamber 1107. Then the slitvalve in apparatus 1102 is opened, and transfer apparatus 1103 entersthe processing chamber and retrieves the processed wafer (1111). Theretrieved wafer is typically transferred via apparatus 103 to anotherprocessing station, then a wafer from the load-lock or from anotherprocessing station is inserted and placed on hearth 1111, after whichthe transfer apparatus withdraws.

[0124] Once a new wafer is on the hearth in the processing chamber, theslit valve associated with apparatus 1102 is closed again, isolating theprocess chamber from transfer chamber 1101. Then process gases areintroduced from unit 1115 through conduit(s) 1114 and pumping speed isthrottled.

[0125] There are, as was briefly described above, many processes thatare accomplished in processing stations of the general nature describedwith reference to FIGS. 10A and 10B. Cleaning, etching, backsputtering,and many different deposition recipes may be accomplished, for example.Typically each process is served by a chamber specifically designed forthat process.

[0126]FIG. 11A is an isometric view of a multipurpose processing station1201 according to a preferred embodiment of the present invention,capable of performing a broad variety of processes, and FIG. 11B is anexploded view of the multipurpose processing station of FIG. 11A. FIG.11C is an isometric, cutaway elevation view of the multipurposeprocessing station shown in FIGS. 11A and 11B, seen from a differentperspective than that of FIG. 11A. FIG. 11D is an elevation section viewof the multipurpose processing station of FIG. 11A, shown in processingmode, and FIG. 11E is an elevation section view of the apparatus of FIG.11A, shown in transfer mode. As the multipurpose station in itsembodiments is a relatively complicated apparatus, several views andsections have been provided to better illustrate the features andelements of the station, and the descriptions which follow bearing onthe multipurpose processing station are best understood by reference toall of the views provided.

[0127] Referring now primarily to FIGS. 11A and 11B, multipurposeprocessing station 1201 is attached to a cluster tool by base chamber1203, which, when assembled with other elements provides vacuumintegrity. Base chamber 1203 has a side extending passage 1205 ending ina flange 1207 which is adapted to mount to a mating flange on a clustertool transfer apparatus in the manner that station 1104 mounts to system1100 (FIG. 10A). A slit valve is not shown, and in this embodiment is apart of the cluster tool apparatus to which flange 1207 mounts.

[0128] A cylindrical (in this embodiment) processing chamber 1204 mountsto an upper end of base chamber 1203 with vacuum seals providing vacuumintegrity at the interface, and a lid assembly 1261 seals to the upperend of the process chamber with vacuum seals. The lid assembly in thisembodiment is hinged to the process chamber and also has apparatus forproviding process gases into the process chamber. The lid assembly andassociated apparatus are described more fully below. For the presentportion of the description it is important to note (FIGS. 11C and 11D)that the process chamber with the lid assembly and pedestal provides aclosed processing volume.

[0129] A drive assembly 1209 mounts below to base chamber 1203 by ahorizontal flange with vacuum seals. The horizontal flange is a part ofan upper cylindrical housing 1211 which has a side outlet 1213 forattachment to a vacuum pumping system not shown. Upper housing 1211, byvirtue of being rigidly mounted to base chamber 1203, which is in turnrigidly mounted to the vacuum transfer chamber of a cluster tool, is astationary element providing structural support for other elements, aswill be clear from further description below.

[0130] The purpose of the drive assembly is to raise and lower aninternal pedestal apparatus 1215 (FIG. 11B). The pedestal apparatus hasa heated hearth for supporting and providing heat to a wafer to beprocessed. When the pedestal is in a lowermost position wafers may beinserted into the base chamber and released to lie upon the hearth, andafter the transfer apparatus withdraws through extension 1205 and theassociated slit valve closes, the pedestal may be raised, moving thesupported wafer up into a process chamber in position to be processed.

[0131] Relationship of pedestal apparatus 1215 to the drive assembly maybest be seen in FIGS. 11C, 11D, and 11E. Pedestal apparatus 1215 has anupper portion 1217 comprising a heater plate, an electrical insulatorplate, and other elements which are described in more detail in sectionsbelow. For the present description regarding the drive assembly, theconnection of the pedestal apparatus to the drive assembly is of primaryinterest.

[0132]FIG. 11E shows pedestal apparatus 1215 in its lowermost positionhaving a wafer 1219 supported on upper portion 1217 of the pedestalapparatus. In this position a transfer apparatus (1103 of FIG. 10A) mayenter the base chamber through extension 1205 and pick and place waferson the upper portion of the pedestal apparatus. For the presentdescription it may be assumed wafer 1219 has been placed on the pedestalapparatus.

[0133] Attention is now directed to upper housing 1211 of drive assembly1209. A rigid lower cylindrical housing 1221, of lesser diameter thanupper housing 1211 extends below upper housing 1211. Pedestal apparatus1215 has an upper structure 1224 and a lower extension 1225 ending in aflange 1227 to which an outer cylindrical member 1223 is also mounted,creating an annular region therebetween. Outer cylindrical member 1223is lined with a bearing material and is adapted to fit closely aroundlower housing 1221, forming thereby a vertical linear guide for raisingand lowering pedestal apparatus 1215 reliably with no eccentric loads.

[0134] Vacuum integrity is maintained for the overall assembly whileallowing vertical freedom of motion for the pedestal apparatus by ametal bellows 1233 which seals between flange 1227 at a lower end and aflange 1229 affixed by its outer diameter to the lower end of lowercylindrical housing 1221. Flange 1229 is stationary, as it is a part oflower housing 1221 attached to housing 1211 which is mounted to basechamber 1203. Flange 1227, by virtue of being attached to lowerextension 1225 of pedestal apparatus 1215, travels up and down withpedestal apparatus 1215. As the pedestal apparatus is lowered, bellows1233 extends, and as pedestal apparatus 1215 is raised, bellows 1233retracts. The pedestal apparatus is restrained in its vertical path bythe inside diameter of flange 1229 and primarily by the internal bearingwithin cylinder 1223.

[0135] In regard to drive assembly 1209 and raising and lowering thepedestal apparatus, it remains to describe the mechanisms by whichpedestal apparatus 215 is translated between the lowermost position(FIG. 11E and the uppermost position (FIG. 11D). Referring now primarilyto FIG. 11A, drive assembly 1209 includes an electrically actuated andpowered linear actuator 1235 in this embodiment having an extensibleshaft 1237 within a guide housing 1238, wherein the extensible shaft maybe extended and retracted within housing 1238 as initiated by controlsignals received from a control system not shown. One end of extensibleshaft 1237 is pivotally attached by a clevis 1239 to upper housing 1211of the drive assembly. A yoke assembly 1241 comprising a U-shaped trackencircles the body of cylinder 1223 (which is fixedly attached topedestal assembly 1215) and is pivotally attached at the ends of theU-shaped track to opposite ends of a clamp bar 1243, and the clamp barclamps on drive housing 1238.

[0136] Referring now to FIGS. 11B and 11C, yoke assembly 1241 engagestwo bearings 1245 which are mounted to opposite sides of cylinder 1223.Referring now to FIG. 11B, at the center of the curved end of theU-shaped track of cam-track/yoke assembly 1241, one end of anadjustable-length link 1247 is pivotally fastened by a clevis 1249. Theopposite end of link 1247 is fastened again to housing 1211 by a clevis1251.

[0137] In the arrangement described above, as extensible shaft 1237 isextended, the yoke assembly is moved as a lever having the attachment atclevis 1249 as a fulcrum, such that cylinder 1223 is lowered a distanceabout one-half the length that shaft 1237 is extended, causing theentire pedestal assembly to be lowered relative to the process chamberand the base chamber. As shaft 1237 is retracted the pedestal assemblyis similarly raised relative to the base and process chambers.

[0138] It will be apparent to those with skill in the art that there areother mechanisms by which the pedestal assembly may be translatedrelative to the base and process chambers, and there are a variety ofalterations in the mechanisms shown that might be made without departingfrom the scope of the invention. There are, for example, a number ofdifferent extensible drives that might be used, such a air cylinders,air-oil systems, hydraulic systems, and the like. The embodimentdescribed provides smooth translation and accuracy.

[0139] In an aspect of the present invention vertical movement of thepedestal assembly, which provides for a lower position for inserting andretrieving wafers through extension 1205, and an upper position whereina wafer on the pedestal is presented upward into the processing chamberfor processing, also provides for a different pumping speed between theupper position and the lower. Also the elements that make this possiblealso allow for easy alteration of the actual pumping speed in theprocess position. These features are best understood with reference toFIGS. 11D and 11E.

[0140] Referring to FIGS. 11D and 11E a ring-shaped liner 1253 ispositioned at the point that base chamber 1203 joins process chamber1204. The inside diameter of liner 1253 determines area of an annularpassage 1255 (FIG. 11D) formed between liner 1253 and the top edge ofpedestal 1215 when the pedestal is in the uppermost position. Liner 1253is also made of a material that has a relatively low coefficient ofconductive heat transfer, and thereby provides protection for the partsof the process chamber and the base chamber that are closest to theheated pedestal while the pedestal is in the processing (uppermost)position.

[0141] In conjunction with liner 1253, pedestal 1215 is provided with anannular shroud 1257 which is attached to the pedestal and forms a shapedpumping annulus. When pedestal 1215 is in the uppermost position theupper annulus that shroud 1257 forms with the body of pedestal 1215mates with annulus 1255 by the upper rim of the shroud mating with liner1253. Referring to FIG. 11D it is clear that the passage for pumpingfrom the process chamber through side outlet pumping port 1213 isthrough the annular passage formed between shroud 1257 and the body ofpedestal 1215.

[0142] Referring now to FIG. 11E, wherein pedestal 1215 has been movedto the lowermost position for transfer of wafers in and out of thestation, it is clear that gases from the process area may still passthrough the shroud annulus described above, but may also pass around theoutside of the shroud through region 1259 and thence to region ofhousing 1211 and out through pumping port 1213.

[0143] It is well-known to those with skill in the art that pumpingspeed needs to be relatively high after processing and during wafertransfer, and has to be throttled to a lower, controlled speed duringprocessing to assure total gas pressure during processing. Inconventional systems this is accomplished by throttling valves and thelike, typically in the pumping port of a chamber. In this aspect of thepresent invention this difference accrues simply by virtue of verticaltranslation of the pedestal assembly with the attached pumping shroud.In this aspect a throttling valve may still be used for precise processpressure control.

[0144] t will be apparent to those with skill in the art that one designfor the liner and shroud will not provide for a broad variety ofprocesses, both CVD and PECVD, which may require quite different pumpingspeeds in process. In the embodiment described of the present invention,for a different process, it is only necessary to remove the pedestal andreplace the shroud and liner, which may be done at a planned downtimefor routine maintenance and cleaning. Moreover, this replacement is arelatively simple matter due to unique design of other aspects Of thechamber, as will be described more fully below.

[0145] Referring now to FIGS. 11A through 11D, the process region isclosed by a lid assembly 1261 comprising a lid ring 1263, an insulatorring 1265 and a gas diffuser assembly 1267. Gas diffuser assembly 1267has ports not shown for introducing process gases, internal passages forconducting the process gases to the process chamber, and diffuserelements within the process region for distributing process gases evenlyover a wafer on pedestal 1215 in position in the process chamber to beprocessed. Such ports, passages and distribution elements are well-knownin the art.

[0146] Diffuser 1267 is nested in an insulator ring 1265 which provideselectrical and thermal insulation for the diffuser assembly, and allowsthe diffuser assembly to be electrically biased relative to otherelements as required in various process recipes. Such bias may be usedto, for example, provide for exciting the process gases in the chamberto form a plasma, as known in plasma-enhanced CVD processes. Insulatorring 1265 joins to lid ring 1263 and to diffuser 1267 in a manner withvacuum seals to provide vacuum integrity and to provide also a rigid lidassembly. In a preferred embodiment lid assembly 1261 is hinged toprocess chamber 1204 with a removable vacuum seal, making access forcleaning and maintenance relatively facile and routine. In otherembodiments the lid may be mounted differently and completely removedfor access.

[0147] Referring now primarily to FIGS. 11D and 11E access to the insideof the process chamber may be made by releasing lid assembly 1261 andmoving it out of the way. At the bottom of station 1201 easy access isprovided to flange 1227 where the lower portion 1225 is fastened toflange 1227. With the lid assembly open one may dismount pedestalassembly 1215 from flange 1227 and remove it from the processing stationout the open top. This feature provides quick and simple access toportions of the processing chamber requiring cleaning and maintenance,and also for trading liners and shrouds to provide new and differentprocessing conditions.

[0148] Significant improvements over prior art have been provided in thearchitecture of the upper portions of pedestal 215. FIG. 12 is a partialcross section through the top region of pedestal 1215 at about theposition of broken circle 1269 in FIG. 11D. As described above and asmay be seen by reference in particular to FIG. 11C, pedestal 1215 is anassembly of an upper structure 1224 and a lower extension 1225. Upperstructure 1224 is closed at the top by a closure plate 1226, andelements 1225, 1226, and 1224 are assembled with vacuum seals providingan essentially hollow vacuum-tight structure. Upper closure plate 1226supports heater and electrode elements for supporting a wafer duringprocessing as described more fully below with reference to FIG. 12.Closure plate 1226 of pedestal assembly 1215 is the base plate in FIG.12, and is water-cooled to maintain operating temperature for vacuumseals, such as conventional o-rings and the like, and for other elementsthat might be damaged by high temperatures..

[0149] Referring now primarily to FIG. 12, closure plate 1226 ispenetrated in this embodiment in two places by a unique electricalfeedthrough unit 1301. One such penetration is shown in FIG. 12, but ina preferred embodiment there are two such penetrations serving a uniqueheater plate to be described in detail below. Feedthrough unit 1301 isadapted to closure plate 1226 with vacuum seals to preserve vacuumintegrity. Feedthrough unit 1301 in one penetration of closure plate1226 provides electrical power to heating elements in a heater plate1303, which is spaced apart from closure plate 1226 by in electricalinsulator plate 1305. The function of heater plate 1303 is to provideheat to a susceptor 1307 upon which a wafer rests during processing.

[0150] Susceptor 1307 is a mostly graphite structure which has a highcoefficient of conductive heat transfer, and is spaced apart from heaterplate 1303 by a small distance D1. Heater plate 1303 provides heat tosusceptor 1307 by convection and radiation across gap D1, helping toprovide a relatively constant temperature across its upper surface,hence over the surface of a wafer, and also providing an efficientelectrode for high frequency electrical biasing. The susceptor forms anelectrical entity which, for those processes requiring it, is biasedthrough an RF feedthrough, not shown in FIG. 12.

[0151] Heater power wires connecting to two feedthroughs 1301, to asecond feedthrough for RF power, and miscellaneous other conduits andconnectors are provided to the region of the lower surface of closureplate 1226 by being guided up through the hollow interior of pedestalassembly 1215 (See FIGS. 11C, D, and E). Such wires and conduits forsupplying power and other utilities to pedestal 1215 subassemblies andelements are not shown in these views to promote simplicity, and extendgenerally from external power and utility supplies as known in the art.

[0152] There are several other vacuum-sealed penetrations throughclosure plate 1226 in the preferred embodiment described herein, but notspecifically shown in the drawing figures. These include thermocoupleswith appropriate feedthroughs for sensing temperature of internalelements and at least one optical sensor for monitoring temperature ofthe susceptor. Such feedthroughs are generally known in the art. Anair-cylinder-operated mechanism for translating a pattern of typicallythree ceramic pins is adapted to the heater/susceptor assembly as well,and is used to raise and lower a wafer from the surface of susceptor1307 to allow a transfer device to extend under a wafer for picking andplacing wafers to and from the susceptor plate. In a preferredembodiment a pneumatic cylinder is adapted to the underside of closureplate 1226 such that the moving haft of the cylinder may be extendedthrough an opening in the closure plate via a bellows seal. Thepneumatic cylinder has a one-half inch stroke and operates a spiderpositioned below the heater that carries three ceramic pins that extendthrough small openings in the heater and the susceptor plate.

[0153] When pedestal 1215 is retracted as shown in FIG. 11E so a wafermay be transferred, a wafer on susceptor 1307 may be lifted off theupper surface of the susceptor by the ceramic pins referred t above,actuated by the pneumatic cylinder described. A transfer arm (see FIG.10A, item 1103) may then extend into the process station beneath the awafer on the pins but above the susceptor. Retracting the pins thenplaces the wafer on the transfer arm, which may then be withdrawn alongwith the wafer. The process may be reversed for placing a new wafer tobe processed on the susceptor.

[0154] Feedthrough 1301 of FIG. 12 is shown isolated in FIG. 13A. Aceramic body portion 1403 is joined by intermetallic bonding in thisembodiment to a metal body portion 1405 which has a seal grove 1407 fora vacuum seal such as an o-ring, forming a unitary body sealable throughan appropriate opening in closure plate 1226 (FIG. 12). Solid nickelwires 1409 are sealed through ceramic body portion 1403 also byintermetallic bonding as known in the art, and are joined toconventional power wires 1411 such as by soldering, at a distance greatenough from the feedthrough that conducted heat will not be a problem.

[0155] On the vacuum side of feedthrough 1301 nickel wires 1409 arejoined to sockets 1413 assembled in openings 1415 in ceramic bodyportion 1403 and adapted for receiving posts from heater plate 1303(FIG. 12). The posts are described more fully below. Sockets 1413 areconstrained in the vertical direction by wires 1409, which haveconsiderable stiffness. Openings 1415 are somewhat larger in diameterthan the diameters of sockets 1413, allowing sockets 1413 lateralfreedom of movement (wires 1409 offer little resistance to lateralmovement). This freedom of lateral movement allows for some movement andmisalignment when assembling a heater plate having posts (as furtherdescribed below) to a closure plate.

[0156]FIG. 13C is a top view of feedthrough 1301 of FIG. 13A, and FIG.13B is a section view taken through the body assembly of feedthrough1301 along section line 13B-13B of FIG. 13C, which is substantiallyrotated ninety degrees from the section of FIG. 13A. Section view 13B isalong a groove 1417 in ceramic body portion 1403 below a circulardeclavity 1419. Declavity 1419 receives a circular portion of heaterplate 1303 from which connector posts extend, and groove 1417 receives abaffle extension 1311 of a ceramic insulator barrier 1309 which servesto prevent line-of-sight electrical interaction between individual postsof the electrical feedthrough.

[0157]FIGS. 14A and B show a top view and a side view of ceramicinsulator barrier 1309, which has an overall diameter great enough toencompass the position of both sockets 1413. Barrier 1309 has circularopenings 1511 and 1513 in this embodiment which are adapted to allowposts assembled to heater plate 1303 to pass through in a manner that isdescribed in more detail below. Baffle extension 1311 of barrier 1309extends as a barrier wall across the diameter of barrier 1309 atsubstantially ninety degrees to the flat body of the ceramic barrier,and is adapted to engage groove 1417 when a heater plate is assembled toa pedestal in the embodiment described.

[0158]FIG. 15A is an isometric view of heater plate 1303 of FIG. 12.FIG. 15B is a plan view of the same heater plate, and FIG. 15C is a sideview. Heater plate 1303 in this embodiment is a unique two-zone heaterhaving an inner region 1603 and an outer region 1605 separated by a dualchannels 1607 and 1609 which pass through the thickness of the heaterplate. Inner region 1603 is adapted to be about the diameter of a waferto be placed on a susceptor over the heater, and outer region 1605encompasses substantially the remainder of the area of the heater plate.Heater plate 1303 in this embodiment is a ceramic assembly withthin-film heating elements.

[0159] Two separate connector-post structures 1611 are constructed onheater plate 1303 in this embodiment, one to serve inner region 1603 andthe other to serve outer region 1605. The provision of two separateregions capable of being powered independently allows tuning heatdistribution to combat edge effects in heating a wafer on a susceptoroverlying the two-zone heater, which allows a wafer to be heated evenlyall the way to the outer diameter, a significant advance over prior artheaters.

[0160]FIGS. 16A, B, and C illustrate a unique connector post 1701 usedin the present embodiment in conjunction with the heater plate andsocket assembly described above with reference primarily to FIGS. 13A,B, and C. FIG. 16A is an isometric view of connector post 1701, FIG. 16Bis an enlarged end view, and FIG. 16C is a section view taken alongsection line 16C-16C of FIG. 16B.

[0161] Connector post 1701 has a threaded portion 1703, a flange 1705and a flexible-finger post extension 1707. The overall length in thepresent embodiment is about one-half inch, with about one-quarter inchdevoted to each of the threaded portion and the post extension, butlarger and smaller posts may be used in other embodiments. The threadfor the threaded portion is preferably a fine thread, but severaldifferent thread sizes may be used.

[0162] In the preferred embodiment shown in FIGS. 16A, B and C postextension 1707 of connector post 1701 is divided into 12 equal flexiblefingers such as fingers 1709 illustrated. The connector post istypically made from a chemically-resistant material such as one ofseveral types of stainless steel, and is heat treated in a manner knownin the art to provide for appropriate spring tension of the fingers.

[0163] Referring now to FIGS. 15A, B and C, each connector-poststructure 1611 has a raised land 1601 with two threaded holes. Aninsulator barrier 1309 is placed on each raised land, and connectorposts 1701 are threaded through openings 1511 and 1513 in the insulatorbarrier such that flanges 1705 capture and hold the insulator barriersagainst the heater plate. This assembly is clearly illustrated withreference to FIG. 12. Heater plate 1303 is designed so that the threadedholes allow each heater post to mate with an appropriate heating elementin the heater plate. It will be apparent to those with skill in the artthat there are many alternative arrangements that might be made inheater design to utilize the unique structure described.

[0164] Referring again to FIG. 12, feedthrough penetrations withfeedthroughs 1301 are provided in closure plate 1226 in the patternrequired to mate with connector-post structures 1611 of a heater plate1303. When a heater plate is assembled to a closure plate, the raisedland 1601 of each connector-post structure engages circular declavity1419 (see also FIGS. 13A and 13B). At the same time baffle extension1311 of insulator baffle 1309 engages groove 1417, creating ano-line-of-sight connection. As described above, sockets 1413 on wires1409 of feedthrough 1301 allow some lateral movement, which, togetherwith the flexible fingers of the posts ensures facile and positiveengagement.

[0165] In the preferred embodiment described herein there are twoconnector-post structures providing power connection to two separateheater regions in a single heater plate. In this embodiment a separatesingle-post structure not illustrated but using the same socket and postarrangement (but single post) provided for high frequency connection forRF biasing in plasma-enhanced CVD (PECVD) processes. It will be apparentto those with skill in the art, however, that there may be more or fewerconnector-post structures, and a dual post feedthrough may well be usedfor high-frequency biasing as well.

[0166] It will be apparent to those with skill in the art that there aremany alterations in detail and scale that may be made in the embodimentsdescribed herein without departing from the spirit and scope of thepresent invention. Many such variations have already been mentioned.There are many others. For example, there are many wafer sizes presentlyin use in integrated circuit manufacturing, and processing stationsaccording top embodiments of the present invention may be constructed toaccommodate individual wafer sizes or a range of wafer sizes. A stationaccording to the invention might, for example, be sized to accommodatewafers of up to 12 inches or more in diameter, but be fitted with heaterstructure to properly, evenly, and efficiently heat a wafer of nominaleight-inch diameter.

[0167] As another example of the breadth of the present invention, driveassembly 1209 described in detail above provides an efficient, smoothand extremely long-life drive for raising and lowering a pedestalassembly in various embodiments of the present invention. There are manyvariations in this drive that might be used, though, and even completelydifferent drives that might be incorporated in some embodiments whileretaining a unique inventive difference over the existing art.

Use of the Multipurpose Processing Chamber for ALD Processes

[0168] In another aspect of the present invention the multipurposeprocess chamber described above with reference to FIGS. 10A through 16Cis used for performing atomic layer deposition (ALD) processes asdisclosed and described above with reference to FIGS. 1A through 9.

[0169] Referring now to FIG. 5, a system arrangement is shown wherein aVESCAR arrangement 27 is interfaced to a vacuum-central substratehandler 23. As was described with reference to FIG. 7, plural VESCARunits could be interfaced to slit valves of the vacuum-central substratehandler. Handler 23 is essentially the same cluster-tool handler asdescribed with the aid of FIG. 10A, and it will be apparent, giving theteachings herein, that either the multipurpose chamber or a VESCAR unit,or one or more of each, may be interfaced to such a cluster-toolhandler.

[0170] In a preferred embodiment of the invention at least onemultipurpose chamber according to the descriptions above is interfacedto a cluster-tool handler, and gas provision and control apparatus isprovided for the multipurpose chamber according to the descriptionsprovided above with reference to FIGS. 8 and 9. Preferably pluralmultipurpose chambers (now ALD chambers) are so interfaced along with atleast one load-lock apparatus so wafers to be coated may be loaded toand unloaded from the affixed ALD chambers. In this way as many wafersas there are ALD chambers may be introduced for each cycle, and eachwafer will have its own dedicated process chamber for the ALD process tobe performed. The processes may be identical, or they may be vastlydifferent, and load, unload, and processing parameters may be programmedto suit.

[0171] Attention is now drawn to FIGS. 11D and 11E, which shown one ofthe multipurpose chambers in a processing position (11D) and in atransfer position (11E). Chamber 1204 in the present aspect is providedin a manner particularly adapted to the size of a wafer to be coated byALD process, minimizing the volume of the chamber consistent with gasflow. The volume of the chamber is established when the pedestal is inits uppermost position, as opposed to the apparently larger volume whenthe pedestal is retracted (FIG. 11E).

[0172] ALD gas provision is through a special lid, shown generically aslid 1267, and special circumstances may be addresses, such as a changein wafer thickness, film material, and so forth, by substituting lids tothe multipurpose chamber. Similarly, the pumping speed for processing isdetermined in the processing position by the annulus 1225 formed whenthe pedestal is in the uppermost position. Pumping requirements may befine-tuned by interchanging rings 1253 (FIG. 11E).

[0173] In operation, pedestals are retracted, finished wafers areunloaded, and new wafers are loaded to each chamber in the cluster-toolarrangement. The slit valve interfaces are closed and pedestals areadvanced. In the process the wafer hearth in each chamber is maintainedat temperature, so the wafers rapidly come up to processing temperature,which may be aided by hot gas infusion. With the wafers a coatingtemperature the gas flows regimen is imposed for each chamber, and theALD process accrues.

[0174] It will be apparent to the skilled artisan that there are manyalterations that may be made in the apparatus and methods describedwithout departing from the spirit and scope of the present invention.Wafers of many different sizes may be processes, for example, bychanging certain elements of the chambers. process parameters may beaccommodated in a wide variety of ways.

[0175] As a further example, there are many material substitutions thatmight be made in many elements of the present invention, such as for thematerial of the heater plate and for the susceptor. In view of the broadrange of variations that may be made, the invention is limited only bythe scope of the claims which follow:

What is claimed is:
 1. An ALD processing station for a cluster toolsystem, comprising: a processing chamber portion having a lowerextremity with a first cross-sectional area; a base chamber portionbelow the processing chamber portion, the base chamber portion having avacuum pumping port and a substrate transfer port, and a secondcross-sectional area below the circular lower extremity of theprocessing chamber and the vacuum pumping port greater than the firstcross-sectional area; a substrate support pedestal having an uppersubstrate support surface with a third cross-sectional area less thanthe first cross-sectional area and adapted to the base chamber portionbelow the transfer port by a dynamic vacuum seal allowing verticaltranslation; a vertical-translation drive system adapted to translatethe substrate support pedestal to place the upper support surface at aprocessing position substantially even with the lower extremity of theprocessing chamber, or at a lower transfer position in the base chamberportion above the pumping port and below the transfer port; and ademountable gas supply lid mounted to the processing chamber, the lidfor providing gases according to an atomic layer deposition (ALD)protocol; wherein, with the substrate support pedestal at the processingposition the cross-sectional area of the substrate support pedestal andthe larger first cross-sectional are of the form a first pumping passagehaving a first total effective area determining a fist limited pumpingspeed from the processing chamber portion through the vacuum pumpingport, and with the substrate support pedestal at the lower transferposition, the cross-sectional area of the substrate support pedestal andthe larger second cross-sectional area form a second annular pumpingpassage having a second effective area greater area than the firsteffective area, allowing a second pumping speed from the processingchamber greater than the first limited pumping speed.
 2. The processingchamber of claim 1 wherein the first cross-sectional area is formed by areplaceable ring, thereby allowing the first pumping speed to beincrementally varied by interchanging replaceable rings having constantouter diameter and differing inner diameter.
 3. The processing chamberof claim 1 further comprising an annular shroud surrounding a portion ofthe substrate pedestal beginning at the upper support surface andextending below the upper support surface, wherein the pumping area ofthe annular shroud at the height of the upper support surface issubstantially equal to the first cross sectional area, such that, withthe substrate support pedestal in the processing position the annularshroud mates with the first cross-sectional area constraining all gasflow from the processing chamber to flow within the annular shroudbetween the annular shroud and the substrate support pedestal.
 4. Theprocessing station of claim 1 wherein the demountable lid closing anupper extremity of the processing chamber is mounted with a demountableseal, such that the lid and the dynamic vacuum seal may be demounted,allowing the substrate support pedestal to be withdrawn from within thebase chamber region upward through the processing chamber region.
 5. Theprocessing station of claim 4 wherein the demountable lid comprises agas distribution system for providing processing gases evenly over anexposed surface of a substrate supported on the substrate supportpedestal with the substrate support pedestal in the processing position.6. The processing station of claim 1 wherein the substrate supportpedestal comprises a closure plate parallel with the upper supportsurface and forming a vacuum boundary for the processing chamber, aheater plate on the processing chamber side thermally-insulated from theclosure plate, and an electrically-isolated susceptor spaced-apart fromand above the heater plate, the susceptor forming the upper supportsurface.
 7. The processing station of claim 6 wherein the heater plateis a composite heater plate having at least two separately-poweredheating regions, allowing temperature profile across the plate to bemanaged by managing power to the separately-powered regions.
 8. Theprocessing station of claim 7 wherein the inner heating region isseparated from the outer heating region by at least one groovesubstantially through the heater plate.
 9. The processing station ofclaim 7 wherein the inner heating region has a cross-sectional aresubstantially equal to the cross-sectional area of a substrate to beheated by the heater plate.
 10. The processing station of claim 1wherein the dynamic vacuum seal is a stainless steel bellows.